For certain construction projects, rigid members, such as piles, anchor members, caissons, sheet pile barriers, and mandrels for inserting wick drain material, must be placed into the earth. The term “piles” will be used herein to refer to the rigid members typically driven into the earth during construction projects. It is well-known that such rigid members may often be driven into or extracted from the earth without excavation by applying a driving or extracting force on an upper end of the pile.
When applying a downward driving force to a pile, it is not necessary, although perhaps desirable, to clamp the pile driver to the pile. However, when a pile is extracted from the earth, a clamp system must be used to transmit an upward extracting force to the pile to pull the pile from the earth. In addition, during both pile driving and pile extracting, a reciprocating vibratory force, typically up and down, may be applied in addition to the driving or pulling force. The use of vibratory forces also requires a clamp system to ensure that the vibratory forces are effectively transmitted to the pile.
A clamp system typically comprises first and second clamp members that engage the pile. A clamping force may be applied to one or both of the clamp members such that the pile or a portion of the pile is securely gripped between the clamp members. The clamp members may be contoured to accommodate the shape of the pile or portion of the pile to be gripped. The clamp members may be otherwise textured in some form to increase friction between the clamp members and the pile.
A primary point of failure of a pile driving or extracting system is when the driving, pulling, and/or vibratory forces are not adequately transmitted to the pile. The need thus exists for improved clamp systems for pile extractors and for pile drivers and extractors that employ vibratory forces.